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Bi2Te3 based alloys have long been the best and most unique thermoelectric materials for power generation below 550 K. Their substitutes with abundantly available elements are highly desirable due to the scarcity of Te element. In this work the band structure calculation of the α-MgAgSb compound shows a narrow gap characteristic. Highly pure α-MgAgSb is obtained by carefully controlled processing. The samples exhibit an intrinsically low thermal conductivity due to the unique crystal structure. A high zT of ∼1.1 at 525 K is achieved in the In doped α-MgAgSb with the optimal carrier concentration of 8–9 × 1019 cm–3, comparable to that of Bi2Te3 based alloys. Considering the abundantly available constituent elements, the present results demonstrate that α-MgAgSb is a promising candidate for low-temperature (RT–550 K) power generation.

Multiferroic materials are of considerable interest due to the intriguing science and application potential. Effects of the Ru dopant on the structural, electrical, domain structure, and ferromagnetic properties of multiferroic BiFeO 3 (BFO) polycrystalline film have been studied. The Ru-doped BFO film (BFRO) possesses a lower electrical conductivity, uniform morphology, larger domain size, and hence fewer domain walls. The BFRO film shows a well-saturated P-E hysteresis loop with an improved remnant polarization close to 99 µC/cm 2 . The saturated magnetizations of the BFO and BFRO film are 8.69 and 16.53 emu/cm 3 , respectively, under a maximum magnetic field of 5000 Oe. The improved ferroelectric, ferromagnetic, and dielectric properties of the BFRO film are ascribed to the reduced concentration of defects and defect dipole complex, valence effect of Ru ions, and a different domain behavior. The enhanced magnetic properties of BFRO arise due to the distorted spin cycloid and canting angle of Fe ions in the Ru-doped BFO film.

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Nonstoichiometric Ag8–xGeTe6 (x = 0, 0.01, 0.02, 0.04) compounds with complex crystal structure are demonstrated to exhibit very low thermal conductivities of <0.28 W/m K, comparable with the calculated theoretical minimum thermal conductivity κmin. Ag deficiency leads to the improved electrical properties and a maximum thermoelectric figure of merit ZT of 0.85 has been obtained at 623 K for Ag7.99GeTe6, about 30% increase compared to that of stoichiometric Ag8GeTe6. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The paper 'The third-body approach: a mechanical view of wear' by Maurice Godet (Wear, 100 (1984), pp 437-452) was perhaps the first to articulate clearly the key role of the rate of debris expulsion from a fretting contact in controlling the overall rate of wear. Whilst subsequent research over the past four decades has acknowledged this, the issue is generally addressed qualitatively rather than quantitatively. There are many parameters which will affect the rate of debris expulsion from a fretting contact, and amongst them is the physical size of the fretting contact. In this paper, for the first time, a physically-based relationship is proposed between the debris-expulsion limited wear rate and the contact size. This relationship is able to account for differences in wear rates observed in tests conducted with different (and evolving) contact geometries (non-conforming contacts) over a range of durations, thus clearly demonstrating the validity of the approach.

Fine-grained binary PbTe thermoelectric materials have been fabricated by a combination of a reflux chemical synthesis and hot pressing. The grain sizes of the hot pressed bulk samples varied from 200 to 400 nm, which significantly contributed to the thermal conductivity reduction due to the enhanced phonon scattering at grain boundaries. Low room temperature thermal conductivity of 0.75 W m−1 K−1 has been obtained after porosity correction for the sample with a grain size of ∼200 nm. The highest figure of merit ZT of the fine-grained binary PbTe bulk sample reaches 0.8 at 580 K although the composition was unoptimized. The value is comparable to that of the best PbTe alloys.

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